A packaging system for "populated" printed circuit boards, i.e., circuit boards on which integrated circuit chips and other components have been installed, must meet two important criteria. First, the packaging must protect the printed circuit board (PCB) from physical shock and vibration. Second, the packaging must protect the PCB against electrostatic discharge. A voltage of less than 100 volts created by an electrostatic discharge can damage some electronic components.
At present, many populated PCB's are placed inside a loose-fitting electrostatic discharge (ESD) bag. The ESD bag and PCB are then placed inside a box or carton and cushioned with antistatic foam. The ESD bag and foam protect the PCB against electrostatic discharge, and the foam guards the PCB against shock or vibration. Alternatively, instead of using antistatic foam, cardboard can be folded inside the box so as to form a protective enclosure around the ESD bag and PCB.
These methods have several disadvantages. Most ESD bags are dark-tinted and difficult to see through. This makes inspecting the PCB difficult unless it is removed from the bag. The antistatic foam is non-biodegradable and therefore creates a disposal problem. Moreover, the box or carton must be made somewhat larger to accommodate the foam.